Method of making incandescent lamps.



W. D. COOLIDGE.

METHOD OF MAKING INCANDESCENT LAMPS.

APPLICATION FILED NOV-7,1910.

1,230,869 Patgnted June 26, 1917;

Witnesses: Inventor:

5M 9/(;ZO1/ William lJCodlidge,

To all whom it may concern:

connection with the. accompanying ductors is as follows? The tungsten powder is rubbed into a vState of New York,

standing of which reference may unrrnn s'rArns PATENT cur os.

winn ng 1). coomnen, or SGHENEC'TADY, nnw Yonx, ASSIGNOR 'ro ennEnAL nnncrnro COMPANY, A oonrona'rio'n on NEW onx.

METHOD OF MAKING INCANDESCENT LAMPS.

1,230,869. Original application filed Julie 14, 1907,

Specification of Letters Patent.

1910. Serial No. 591,187.

Be it known that 1,.W1LLIAM' -D. Coon- IDGE, a citizen of the United States, residing at Schenectady, county of Schenectady, have invented certain new and useful Improvements in Methods of Making Incandescent Lamps, (division of my application filed June 14:, 1907, Serial No. 378,936,) of which the following is a specification. Y

My present invention has for its object a method of assemblin tungsten lamps which consists in winding t e tungsten filament on a spider, similar, for instance, to those used in" tantalum lamps, while the tungsten filament is in a heated and pliant condition.

The scope of myinv'ention ispointed out in the appended claims, for avbetter underbe had to the following detailed description taken in drawings, in which the figure is a-perspective ,view of a lamp made according to the pro .cedure herein disclosed.

Tungsten powder of relatively good quality. can be readily produced by reduction of tungsten tri-oxid with hydrogen according to well -knownchemical methods. The powder so obtained is non-coherent and ex ceedingly refractory but can be shaped into 'coherent conductors suitable for the practice of my present invention. Several methods of constructing such coherent conductors are known in-the'art but the onepreferred by me in the practice of my present invention is claimed by me in this application as it forms the subject-matter of my application, Serial No. 377,781, filed June 7, 1907, issued as Patent No. 1,026,343, May 14, 1912. This preferred method of making coherent conwarm and plastic amalgam, consisting of say equal parts of cadmium and mercury,

. -forming a homogeneous'ductile ixture; the

' tungsten may be added in the proportion of 30 per cent. or more by weight of the final mixture. This mixing operation may be carried out in an ordinary chemists mortar rubbing the materials with a pestle. The product thus obtained may be squirted warm through a diamond die and may be' otherwise manipulated without dilficulty.

The squirted wires probably consist of a mere mechanical mixture of the tungsten powder with the amalgam. The proportion Patented June 26, 191-7. Serial No. 378,936. Divided-and this appl ioation filed November -7,

of mercury and cadmium in the amalgam may be varied through relatively wide limits and a very suitable mixture consists of 44 parts cadmium to 56 parts mercury. Other binders can be used in place of the cadmium amalgam, as for instance cadmiumbismuth alloy having 112 parts cadmium to.

208 parts bismuth; or an alloy containing mercury-cadmium and bismuth in the following proportions: mercury 53 parts, cadmium 42 parts and bismuth 5 parts. It will be noted that all. the materials of the binder have relatively low vaporization points and can therefore be distilled at low tempera- 'tures.

To remove the vaporizable components above mentioned, I may bake the wires in an evacuated tube to the temperature at which most of the mercury and part of the cadmium vaporize out; this leaves a relatively strong and somewhat brittle residue, consisting mainly oftungsten and cadmium, and also bismuth, if the latter has been used in the binder. The wires may then be removed from the baking receptacle andIsusconductive metal clips or terminals ina treating bulbor tube and there subjected to the heating action of current passed through the wires. A vacuum or inert atmosphere should be maintained about the wires during this treatment. The

pended between current distils or vaporizes the remaining cadmium or other component of the binding material'and then consolidates the porous.

homogeneous and residue of tungsten into a The tungsten parrelatiyely compact wire. ticles seem to sinter together and thus decrease the porosity of the structure. The wire shrinks in length very materially during. treatment. The wire is then allowed to cool and wherttaken from the treating chamber is found to be. strong and firm and some what elastic but without the capability of taking a permanent set and practically devoid of ductility, at least in the sense in which that term is applied to such metals as copper, silver, platinum, etc.

To construct a tun ten lamp herent conductor prof or in any other suitable manner, I proceed by winding the conductor on a spider or from a couced as above described supporting frame, similar, those used in tantalum lamps, while maintaining the tungsten in a pliant condition by the application of heat. The tungsten conductor may be heated by the continuous passage of current through it or in any other suitable way. I may even secure the desired mobility by merely heating the ends of the supporting spider while the filament is being bent around them. As soon as the tungsten is heated sufiiciently it becomes soft and feels pliant like copper wire. All these manipulations can be carried out while the tungsten is at a temperature somewhat above room temperature, but lower than visible redness and lower than the temperature at which tungsten appearsto oxidize in air.-

The manipulations can, ducted in open air.

' The finished product may take the form shown in the drawing wherein the bent therefore, be convtungsten filament 1 is shown mounted'on for instance, to 7 sponding to visible redness, and winding the filament on temperature.

.2. The process of mounting. a continuous brittle tungsten filament on the'supports of an incandescent lamp whichconsists in heat,- ing the portions. to be bent while exposed to the atmosphere to a temperature that renders them pliable and is below that of appreciable oxidation and belowthat corresponding to visible redness ofthe filament, and stringing the filament on said supports in the open air while said filament and said supports are exposedto permit manipulation of the filament. Y

' 3. The process of mounting a continuous sintered tungsten filament in zigzag form on the supports of an incandescent lamp which consists in rendering the filament pliant by passing current through it to heat itwhile exposed to the atmosphere to a temperature below that which corresponds to visible redness of the filament and below said supports while atsaid' that at which appreciable oxidation takes place, and stringing said filament while still hot and pliant on'said supports with said filament and said supports .in the open air. In witness whereof, I have hereunto set my hand this 4th day ofNovember, 1910.

' WILLIAM D. COOLIDGE. Witnesses:

.BENJ'AMIN B. HULL, HELEN ORFORD.\ 

